The invention relates to a method of transferring a substantially disc-shaped workpiece. The invention further relates to a device for carrying out this method.
A temporary gluing on so-termed workpiece carriers, in particular carrier discs or carrier plates, is a suitable procedure in the case of one-sided or two-sided surface treatments of substantially planar, in particular very thin and brittle workpieces while this treatment is being carried out so as to avoid a deformation of the workpieces or indeed fracture thereof. A very thin workpiece in the present context should be understood to be a workpiece whose thickness is small in relation to its length, width, or diameter.
The German patent document 198 50 873 laid open to public inspection discloses a method of processing a substantially disc-shaped semiconductor technology product which comprises a plurality of electronic circuit bodies along at least a first main surface as well as a second main surface situated opposite the first main surface. In this method of carrying out treatment processes on one of the main surfaces of the product, a layer-type adhesive material is planarly provided on the opposite main surface of the product, onto which material a dimensionally at least substantially stable carrier element is provided so as to form a planar connection to said opposite main surface of the product.
The invention has for its object to provide a method by which a simple and inexpensive transfer of a workpiece of the kind mentioned above from a first workpiece carrier onto a second workpiece carrier is rendered possible. The invention further has for its object to provide a device for carrying out such a method.
According to the invention, this object is achieved by means of a method of transferring a substantially disc-shaped workpiece from a first workpiece carrier, on which the workpiece is adhesively connected along a first of its main surfaces by means of a first adhesive in an at least substantially planar manner, onto a second workpiece carrier, which method according to the invention comprises the following process steps:
fastening the second workpiece carrier with at least substantially planar adhesion to a second of the main surfaces of the workpiece opposed to the first main surface by means of a second adhesive whose adhesive force is substantially greater than the adhesive force of the first adhesive,
fastening the first workpiece carrier to a first retaining device,
fastening the second workpiece carrier to a second retaining device, separating the workpiece from the first workpiece carrier along the first adhesive through the application of a pulling force between the first and the second retaining device, which force is at least partly perpendicular to the main surfaces of the workpiece,
separating the first workpiece carrier from the first retaining device, and separating the second workpiece carrier complete with the workpiece connected thereto from the second retaining device.
The workpiece is accordingly present on the first workpiece carrier, to which it was fastened by its first main surface by means of the first adhesive, at the start of the process steps according to the invention. The workpiece is transferred from this first workpiece carrier onto a second workpiece carrier by means of the method according to the invention, on which second carrier it is arranged with at least substantially planar adhesion along its second main surface. The connection between the second main surface of the workpiece and the second workpiece carrier is achieved here by the second adhesive whose adhesive force is substantially greater than the adhesive force of the first adhesive, so that the first adhesive is reliably separated when the pulling force is applied between the retaining devices, whereas the second adhesive keeps the workpiece fixed to the second workpiece carrier. The retaining devices here serve to transmit the pulling force to the workpiece carriers and are separated from the workpiece carriers again after the transfer of the workpiece has been completed.
The method according to the invention renders it possible in an inexpensive and simple manner to transfer mechanically vulnerable workpieces safely from one workpiece carrier to another. A separate treatment of the first adhesive for changing the adhesive force before the transfer of the workpiece is not necessary.
In particular, at least substantially rigidly constructed workpiece carriers can be used here.
The fastening of the workpiece carriers to the retaining devices may be achieved by means of adhesives or by magnetic forces, as desired. Said adhesives or magnetic forces will generate adhesive forces between the workpiece carriers and the retaining devices which are substantially greater than the adhesive force of the first adhesive, so that the workpiece carriers remain securely connected to the retaining devices when the pulling force is exerted.
The separation of the workpiece carriers from the retaining devices after the transfer of the workpiece is preferably achieved by means of an ejection device forming part of at least one of the retaining devices. This ejection device advantageously operates at least one ejector pin or a pressure gas device when carrying out the separation step so as to exert a pressure on the workpiece to be separated.
In an alternative advantageous embodiment of the method according to the invention, the workpiece carrier is arranged on a support element in at least one of the retaining devices in which the fastening of the workpiece carrier is achieved by means of said magnet device, which support element is movable with respect to a magnet device and is of a substantially planar construction. The support element is moved together with the workpiece carrier from the operational reach of the magnet device for separating the workpiece carrier from the retaining device. This removal may preferably be achieved in that at least one of the workpiece carriers is arranged on a first support element, preferably of planar steel sheet on rollers, and the workpiece carrier is transferred to a second planar sheet support element through rolling of the first planar sheet support element for the purpose of separation from the retaining device.
Further embodiments and details of the method according to the invention are defined in the dependent claims following claim 1.
To carry out the method according to the invention, furthermore, a device is provided for transferring a substantially disc-shaped workpiece from a first workpiece carrier, on which the workpiece is adhesively connected in an at least substantially planar manner along a first of its main surfaces by means of a first adhesive, onto a second workpiece carrier on which the workpiece is to be provided and fastened with at least substantially planar adhesion by a second of its main surfaces opposed to the first main surface of the workpiece by means of a second adhesive whose adhesive force is substantially greater than the adhesive force of the first adhesive. In addition to the workpiece carriers for fastening the workpiece, the device according to the invention also comprises a first retaining device for fastening the first workpiece carrier to this first retaining device and a second retaining device for fastening the second workpiece carrier to this second retaining device.
A device according to the invention is preferably used for handling a workpiece which is a semiconductor technology product, preferably a semiconductor wafer, and which furthermore is constructed along at least its second main surface for forming a plurality of electronic circuit bodies which are to be mechanically separated substantially perpendicularly to the second main surface. The invention in that case renders it possible to present the workpiece on the second workpiece carrier for a subsequent treatment of its first main surface in a simple manner by means of the transfer that can be carried out thereby, for example for a process step for thinning, coating, or the like.
Further embodiments and details of the device according to the invention can be found in the dependent claims following the independent claim 13.
The device according to the invention is of a simple construction and renders possible a reliable, inexpensive, and thus rational manufacture.